Question

我正在开发一款Android应用。在我的应用程序中，我需要使用选项卡。但是当我在代码中向TabLayout添加选项卡时，它会抛出错误。我的代码出了什么问题？

这是自定义操作栏中的tablayout XML：

<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
    <RelativeLayout
        android:background="@color/colorPrimary"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:paddingTop="@dimen/action_bar_padding_top"
        android:paddingBottom="@dimen/action_bar_padding_bottom"
        android:paddingLeft="@dimen/action_bar_padding_left"
        android:paddingRight="@dimen/action_bar_padding_right">
        <ImageButton
            android:id="@+id/open_left_drawer_icon"
            android:background="@drawable/nav_open"
            android:layout_width="@dimen/nav_icon_width"
            android:layout_height="@dimen/nav_icon_height" />

        <TextView
            android:layout_centerHorizontal="true"
            android:text="@string/app_name"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textSize="@dimen/main_logo_text_size"/>

        <ImageButton
            android:layout_alignParentRight="true"
            android:background="@drawable/wishlist_icon"
            android:layout_width="@dimen/nav_icon_width"
            android:layout_height="@dimen/nav_icon_height" />
    </RelativeLayout>
    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">
        <android.support.design.widget.TabLayout
            android:id="@+id/tab_layout"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_below="@+id/main_tab_layout"
            android:background="?attr/colorPrimary"
            android:elevation="6dp"
            android:minHeight="?attr/actionBarSize" />
    </LinearLayout> </LinearLayout>

我如何在活动中将标签设置为tablayout：

public class MainActivity extends AppCompatActivity {

private TabLayout tabLayout;

 @Override
    protected void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
         tabLayout = (TabLayout)findViewById(R.id.main_tab_layout);

         setupTabs();
     }
      private void setupTabs() {
        tabLayout.addTab(tabLayout.newTab().setTag(1).setText("TRENDY/HOT"));
        tabLayout.addTab(tabLayout.newTab().setTag(2).setText("MEN"));
        tabLayout.addTab(tabLayout.newTab().setTag(3).setText("WOMEN"));

        tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
            @Override
            public void onTabSelected(TabLayout.Tab tab) {
                switch (tab.getPosition()){
                    case 1:

                        break;
                    case 2:

                        break;
                    default:

                        break;
                }
            }

            @Override
            public void onTabUnselected(TabLayout.Tab tab) {

            }

            @Override
            public void onTabReselected(TabLayout.Tab tab) {
                switch (tab.getPosition()){
                    case 1:

                        break;
                    case 2:

                        break;
                    default:

                        break;
                }
            }
        });
    }
}

这是运行应用程序时logacat中的错误：

03-10 12:52:12.610 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion W/dalvikvm: VFY: unable to resolve virtual method 496: Landroid/content/res/TypedArray;.getType (I)I
03-10 12:52:12.610 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion D/dalvikvm: VFY: replacing opcode 0x6e at 0x0002
03-10 12:52:12.618 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion D/dalvikvm: GC_FOR_ALLOC freed 143K, 10% free 2617K/2892K, paused 3ms, total 4ms
03-10 12:52:12.670 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion D/dalvikvm: GC_FOR_ALLOC freed 21K, 10% free 2870K/3168K, paused 1ms, total 2ms
03-10 12:52:12.706 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion D/dalvikvm: GC_FOR_ALLOC freed 98K, 12% free 2992K/3392K, paused 3ms, total 3ms
03-10 12:52:12.710 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion I/dalvikvm-heap: Grow heap (frag case) to 4.121MB for 1127532-byte allocation
03-10 12:52:12.718 7428-7430/com.blog.waiyanhein.mmfashion.mmfashion D/dalvikvm: GC_CONCURRENT freed <1K, 9% free 4093K/4496K, paused 2ms+1ms, total 7ms
03-10 12:52:12.722 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion D/dalvikvm: GC_FOR_ALLOC freed <1K, 9% free 4094K/4496K, paused 2ms, total 2ms
03-10 12:52:12.726 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion I/dalvikvm-heap: Grow heap (frag case) to 6.541MB for 2536932-byte allocation
03-10 12:52:12.734 7428-7430/com.blog.waiyanhein.mmfashion.mmfashion D/dalvikvm: GC_CONCURRENT freed 0K, 6% free 6571K/6976K, paused 1ms+1ms, total 4ms
03-10 12:52:12.774 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion D/AndroidRuntime: Shutting down VM
03-10 12:52:12.774 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion W/dalvikvm: threadid=1: thread exiting with uncaught exception (group=0xa61d4908)
03-10 12:52:12.774 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime: FATAL EXCEPTION: main
03-10 12:52:12.774 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime: java.lang.RuntimeException: Unable to start activity ComponentInfo{com.blog.waiyanhein.mmfashion.mmfashion/com.blog.waiyanhein.mmfashion.mmfashion.MainActivity}: java.lang.NullPointerException
03-10 12:52:12.774 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
03-10 12:52:12.774 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
03-10 12:52:12.774 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at android.app.ActivityThread.access$600(ActivityThread.java:141)
03-10 12:52:12.774 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
03-10 12:52:12.774 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at android.os.Handler.dispatchMessage(Handler.java:99)
03-10 12:52:12.774 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at android.os.Looper.loop(Looper.java:137)
03-10 12:52:12.774 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at android.app.ActivityThread.main(ActivityThread.java:5041)
03-10 12:52:12.774 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at java.lang.reflect.Method.invokeNative(Native Method)
03-10 12:52:12.774 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at java.lang.reflect.Method.invoke(Method.java:511)
03-10 12:52:12.774 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
03-10 12:52:12.774 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
03-10 12:52:12.774 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at dalvik.system.NativeStart.main(Native Method)
03-10 12:52:12.774 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:  Caused by: java.lang.NullPointerException
03-10 12:52:12.774 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at com.blog.waiyanhein.mmfashion.mmfashion.MainActivity.setupTabs(MainActivity.java:395)
03-10 12:52:12.774 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at com.blog.waiyanhein.mmfashion.mmfashion.MainActivity.onCreate(MainActivity.java:98)
03-10 12:52:12.774 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at android.app.Activity.performCreate(Activity.java:5104)
03-10 12:52:12.774 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
03-10 12:52:12.774 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
03-10 12:52:12.774 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230) 
03-10 12:52:12.774 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at android.app.ActivityThread.access$600(ActivityThread.java:141) 
03-10 12:52:12.774 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234) 
03-10 12:52:12.774 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at android.os.Handler.dispatchMessage(Handler.java:99) 
03-10 12:52:12.774 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at android.os.Looper.loop(Looper.java:137) 
03-10 12:52:12.774 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at android.app.ActivityThread.main(ActivityThread.java:5041) 
03-10 12:52:12.774 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at java.lang.reflect.Method.invokeNative(Native Method) 
03-10 12:52:12.774 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at java.lang.reflect.Method.invoke(Method.java:511) 
03-10 12:52:12.774 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793) 
03-10 12:52:12.774 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560) 
03-10 12:52:12.774 7428-7428/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at dalvik.system.NativeStart.main(Native Method) 
03-10 12:52:12.778 396-407/system_process W/ActivityManager:   Force finishing activity com.blog.waiyanhein.mmfashion.mmfashion/.MainActivity
03-10 12:52:12.898 396-407/system_process D/dalvikvm: GC_FOR_ALLOC freed 175K, 35% free 6244K/9560K, paused 16ms, total 16ms
03-10 12:52:12.898 396-407/system_process I/dalvikvm-heap: Grow heap (frag case) to 7.042MB for 856092-byte allocation
03-10 12:52:12.910 396-411/system_process D/dalvikvm: GC_FOR_ALLOC freed 4K, 32% free 7075K/10400K, paused 12ms, total 12ms
03-10 12:52:12.938 396-399/system_process D/dalvikvm: GC_CONCURRENT freed 7K, 31% free 7191K/10400K, paused 9ms+1ms, total 28ms
03-10 12:52:12.938 396-412/system_process D/dalvikvm: WAIT_FOR_CONCURRENT_GC blocked 4ms

为什么无法将标签设置为TabLayout？但是当我在onCreate中删除调用setUpTabs函数时，app运行正常。

Answer 1

您的xml中的TabLayout ID是@+id/tab_layout"，但您在活动中找到了ID为main_tab_layout的视图。

行tabLayout = (TabLayout)findViewById(R.id.main_tab_layout);

应为tabLayout = (TabLayout)findViewById(R.id.tab_layout);

Answer 2

我相信你引用了错误的tablayout。

你定义android：id =＆＃34; @ + id / tab_layout＆＃34;在您的xml中，但您正在寻找tabLayout =（TabLayout）findViewById（R.id.main_tab_layout）;.

尝试将findViewById（R.id.main_tab_layout）更改为findViewById（R.id.tab_layout）。

如果这不起作用，你可以包括其余的XML吗？

无法在Android中向TabLayout添加标签

2 个答案: